URL mapping with C# HttpListener

You can get a similar effect without attributes

HttpListener listener = new HttpListener();
listener.Prefixes.Add("http://*:8080/");
listener.Start();
while (true)
{
    HttpListenerContext ctx = listener.GetContext();
    ThreadPool.QueueUserWorkItem((_) =>
    {
        string methodName = ctx.Request.Url.Segments[1].Replace("https://stackoverflow.com/", "");
        string[] strParams = ctx.Request.Url
                                .Segments
                                .Skip(2)
                                .Select(s=>s.Replace("https://stackoverflow.com/",""))
                                .ToArray();


        var method = this.GetType().GetMethod(methodName);
        object[] @params = method.GetParameters()
                            .Select((p, i) => Convert.ChangeType(strParams[i], p.ParameterType))
                            .ToArray();

        object ret = method.Invoke(this, @params);
        string retstr = JsonConvert.SerializeObject(ret);
    });

Usage would be:

http://localhost:8080/getPersonHandler/333

if you really want to use Attributes then

HttpListener listener = new HttpListener();
listener.Prefixes.Add("http://*:8080/");
listener.Start();
while (true)
{
    HttpListenerContext ctx = listener.GetContext();
    ThreadPool.QueueUserWorkItem((_) =>
    {
        string methodName = ctx.Request.Url.Segments[1].Replace("https://stackoverflow.com/", "");
        string[] strParams = ctx.Request.Url
                                .Segments
                                .Skip(2)
                                .Select(s=>s.Replace("https://stackoverflow.com/",""))
                                .ToArray();

        var method = this.GetType()
                            .GetMethods()
                            .Where(mi => mi.GetCustomAttributes(true).Any(attr => attr is Mapping && ((Mapping)attr).Map == methodName))
                            .First();

        object[] @params = method.GetParameters()
                            .Select((p, i) => Convert.ChangeType(strParams[i], p.ParameterType))
                            .ToArray();

        object ret = method.Invoke(this, @params);
        string retstr = JsonConvert.SerializeObject(ret);
    });
}

Then you can use as http://localhost:8080/Person/333 and your definitions would be

class Mapping : Attribute
{
    public string Map;
    public Mapping(string s)
    {
        Map = s;
    }
}

[Mapping("Person")]
public void getPersonHandler(int id)
{
    Console.WriteLine("<<<<" + id);
}